CVE-2024-21412 is a high-severity vulnerability identified in Microsoft Windows 11 version 21H2, specifically related to the handling of Internet Shortcut files. The vulnerability is categorized under CWE-693, which corresponds to a Protection Mechanism Failure. This indicates that a security control intended to prevent unauthorized or malicious actions is either bypassed or improperly implemented. In this case, the flaw allows an attacker to bypass security features associated with Internet Shortcut (.url) files. These files are commonly used to link to web resources and can be manipulated to execute unintended actions. The CVSS 3.1 base score of 8.1 reflects a high impact, with the vector indicating that the attack can be performed remotely over the network (AV:N), requires no privileges (PR:N), but does require user interaction (UI:R). The scope is unchanged (S:U), but the impact on confidentiality and integrity is high (C:H/I:H), while availability is not affected (A:N). The exploitability is rated functional (E:F), and the report confidence is confirmed (RC:C). Although no known exploits are currently reported in the wild, the vulnerability presents a significant risk due to the ease of exploitation and the potential for attackers to execute malicious payloads or commands by tricking users into opening specially crafted Internet Shortcut files. This could lead to unauthorized disclosure of sensitive information or unauthorized modification of system or user data. The lack of available patches at the time of reporting increases the urgency for mitigation efforts.

For European organizations, this vulnerability poses a substantial risk, especially in sectors with high reliance on Windows 11 21H2 environments, such as finance, healthcare, government, and critical infrastructure. An attacker exploiting this vulnerability could bypass security mechanisms to execute malicious code or commands, potentially leading to data breaches, intellectual property theft, or disruption of business operations. The requirement for user interaction means phishing or social engineering campaigns could be effective vectors, increasing the risk in organizations with less mature security awareness programs. Confidentiality and integrity impacts are high, which could result in exposure of sensitive personal data protected under GDPR, leading to regulatory penalties and reputational damage. Additionally, the vulnerability could be leveraged as an initial foothold for more extensive attacks, including lateral movement within networks. Given the widespread deployment of Windows 11 in enterprise environments, the scope of affected systems is broad, amplifying the potential impact across European organizations.

To mitigate this vulnerability effectively, European organizations should implement a multi-layered approach beyond generic patching advice. First, enforce strict email and web filtering policies to block or quarantine emails containing suspicious Internet Shortcut files or attachments. Deploy endpoint protection solutions capable of detecting and blocking malicious .url file behaviors. Enhance user awareness training focused on recognizing phishing attempts involving shortcut files and the risks of opening unsolicited links. Utilize application control policies (e.g., Windows Defender Application Control) to restrict execution of unauthorized scripts or files originating from Internet Shortcut files. Employ network segmentation to limit the potential spread of an attack if exploitation occurs. Monitor logs and endpoint telemetry for unusual activity related to Internet Shortcut file handling. Since no official patch is available yet, consider temporary workarounds such as disabling the handling of Internet Shortcut files in environments where feasible or restricting file associations. Maintain close communication with Microsoft for updates and apply patches promptly once released. Finally, conduct regular vulnerability assessments and penetration testing to identify and remediate exposure to this and related vulnerabilities.